THE BROAD TAPE-WORM OF SHEEP. 



TiENIA EXP ANSA, Rad. 

 Plates XIV and XV. 



Tcmia expansa, the Broad Tape- worm, is one of the best known of the 

 internal parasites of sheep, because of its flatness, length, and large 

 size. In summer and fall it is quite abuudant. ' The amount of pecun- 

 iary losses occasioned bj' its ravages depend upon the season and its 

 abundance in affected flocks. It was introduced into tiiis country from 

 Europe along with the imported flocks which harbored it. Siuce then 

 it has been parasitical on our flocks from generation to generation. It 

 is now distributed from the wooded hillsides of New England to the 

 grazing lands of Georgia, over the fertile prairies of Ohio, Illinois, Iowa, 

 and Nebraska, and the boundless prairies, basins, and mesas of Colorado, 

 Utah, California, and Oregon ; in short, over every sheep-grazing local- 

 ity in the United States. Reported outbreaks from this vast extent of 

 country are comparatively few and scattered, but are suflScient to warn 

 us that when the pastures become narrowed, older, and overstocked, we 

 may expect the same trouble with this and other parasites as has been 

 experienced by sheep raisers through all time in the more densely pop- 

 ulated districts of other countries. 



Description. — The entire worm measures in length about 5 yards, and 

 in width from one-twenty-fifth of an inch at the head to a half or three- 

 quarters of an inch at the tail. Its thickness is from one-tenth to one- 

 twelfth of an inch. These dimensions vary greatly, depending 0:1 the 

 contracted condition of the worm when measured Jind on its state of pre- 

 servation. Adult specimens taken from sheep may average less than 4 

 yards, or may slightly exceed 5 ; but they never, in this country at least, 

 attain that gigantic measurement of 100 feet ascribed to them by Eu- 

 ropean observers. The head is somewhat larger than the neck, and 

 measures one-twenty-flfth of an inch in width. It is smooth on the end 

 and has its four suckers directed anteriorly. Its neck, or that portion of 

 the worm immediately succeeding the head, which is uusegmented, is 

 short or lacking. The bodyof the worm is apparently made up of aseries 

 of very short but extremely wide joints, which vary in length and width 

 iu the successive portions of the body. The first rings of the tc^nn are 

 very short and narrow; tbo others are longer, but are always broaclep 

 tUau long. Those segujeuts wUicU are about two tbivUs tUe entire leiigtb 

 33038 A P-— 8 ^i3 



